The present disclosure relates to a secondary battery and a battery module including the secondary battery.
Along with the size reduction of portable wireless devices such as video cameras, mobile phones, portable computers, and digital cameras, and the advance and high functionality trend in electric vehicles, secondary batteries generally used as power sources of such devices are required to have small sizes, high energy density, and superior charge-discharge characteristics.
Examples of secondary batteries include nickel-cadmium batteries, nickel metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. In particular, lithium secondary batteries have long lifespans and high energy densities. Lithium secondary batteries may be classified according to the types of electrolytes. For example, lithium metal batteries and lithium ion batteries use liquid electrolytes, and lithium polymer batteries use solid polymer electrolytes.
Although lithium secondary batteries have the above-mentioned merits, lithium secondary batteries may undergo abnormal situations such as internal short circuits, overcharging, and heating. In such situations, electrolytes of lithium secondary batteries may decompose and generate high-pressure gas, and thus the lithium secondary batteries may be deformed or decreased in lifespan.
In particular, if secondary batteries swell, the secondary batteries may explode or catch on fire, and thus measures for guaranteeing safety are required.